Conventionally, a display device capable of displaying a stereoscopic (three-dimensional) image has been proposed. Also, a demand has arisen for a display device capable of selectively displaying a two-dimensional (2D) image and three-dimensional (3D) image, and techniques meeting this demand have been proposed.
For example, JP-A 2000-102038 (KOKAI) describes a technique of switching 2D display and 3D display by using a liquid crystal lens array element. This liquid crystal lens array element includes rod-like electrodes periodically arranged on one substrate, and produces an electric field distribution with respect to an electrode formed on an opposing substrate. This electric field distribution changes the orientation of a liquid crystal layer, and generates a refractive index profile acting as a lens. Since the lens action can be turned on and off by controlling voltages to be applied to the electrodes, 2D display and 3D display can be switched. A system of controlling the orientation direction of liquid crystal molecules by an electric field as described above is called a liquid crystal gradient index (GRIN) lens system. In this arrangement, a 3D display voltage or 2D display voltage is applied to each rod-like electrode. This makes it possible to partially switch 2D display and 3D display in a direction in which the rod-like electrodes are arranged.
In addition, JP-A 2004-258631 (KOKAI) describes an arrangement including a variable polarization cell in addition to a liquid crystal lens array element. In this arrangement, it is possible to partially switch 2D display and 3D display by switching, in the display plane, the polarized states of light entering the liquid crystal lens array element.
Also, JP-A 2004-258631 (KOKAI) has proposed a flag-bit driving method as a driving method of controlling the above-described variable polarization cell. This facilitates driving for implementing the partial display of 2D display and 3D display by grouping a plurality of electrodes of the variable polarization cell.
In the 2D/3D display switching display described in JP-A 2000-102038 (KOKAI), however, the rod-like electrodes are arranged in only the horizontal direction. Consequently, 2D display and 3D display can be switched on the full screen. Also, 2D display and 3D display can partially be switched in the horizontal direction. However, the screen cannot be split in the vertical direction.
In addition, in the display described in JP-A 2004-258631 (KOKAI) or JP-A 2010-78653 (KOKAI), the screen can be split not only in the horizontal direction but also in the vertical direction. However, the variable polarization cell is necessary in addition to the liquid crystal GRIN lens element. This increases the thickness and weight, and raises the cost.